Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!apple!veritas!amdcad!jetsun!weaver From: weaver@jetsun.weitek.COM (Mike Weaver) Newsgroups: comp.arch Subject: Re: Cordic Math Algorithms Message-ID: <1991May1.171420.11826@jetsun.weitek.COM> Date: 1 May 91 17:14:20 GMT References: <2548@spim.mips.COM> <3394@crdos1.crd.ge.COM> <41842@cup.portal.com> Reply-To: weaver@jetsun.WEITEK.COM (Michael Weaver) Distribution: usa Organization: WEITEK, Sunnyvale CA Lines: 27 In article <41842@cup.portal.com> waw@cup.portal.com (Warren Charles Wong) writes: >Hello, > >Recently, I've come across some terminology regarding floating-pt >algorithms used in PostScript character generations. A popular one >I've heard is the "Cordix" algorithm... That's CORDIC (an acronym). I don't have the book here but I believe there is a reprint of the original paper by Walthers in 'Computer Aritihmetic', Vol. I, Swartzlander, Ed. CORDIC is a family of algorithms for computing elementary functions (trig, hyperblolic trig, polar to/from rectangular coordinates, rotations, linear transformations, perhaps others). The algorithms are iterative, and take one iteration per result bit. By my thinking, this is slow, but speed is relative. On the other hand, the only hardware required is an adder and a shift by one place. CORDIC has been used in floating point coprocessors (Motorola 68881 I believe) and hand held calculators (HP I believe). If you already have fast floating point hardware, there are probably faster algorithms. However, if you only have an integer unit, these may be interesting. --- Michael Weaver.